Mission Aircrew Course CAP Grid Systems

Aircrew Tasks O-2003 GRID SECTIONAL CHARTS (P)

Objectives Given Attachment E of the U.S. National SAR Supplement to the International Aeronautical and Maritime SAR Manual, grid a sectional. State the size of a full and a one-quarter conventional grid. Given coordinates and a sectional, use the Cell Grid System to draw a search grid. State the size of a full and a one-quarter Cell grid system grid.

Locating a Position Use a system of imaginary lines Some run north and south (latitude) Others run east and west (longitude) Where they cross defines a point on the earth By convention, latitude is stated first Points are defined as x degrees of latitude and y degrees of longitude.

Latitude Lines of latitude run east and west Latitude starts with 0°at the equator Latitude increases to 90°north at the North Pole and 90°south at the South Pole Great Circle and Lesser Circles North Latitudes The Equator is a Great Circle and all other lines of latitude are lesser circles. Equator South Latitudes

Longitude Longitude has to start someplace West Longitude East Longitude Longitude has to start someplace So 0° is in Greenwich England East and west longitude increase as you move away from the Prime Meridian The Prime Meridian is a Great Circle and all other lines of longitude are lesser circles. Prime Meridian

Sectional Aeronautical Charts 1 to 500,000 Medium to slow speed aircraft Types of Information: Legend, Aeronautical, Topographical 8.10.1 Objective 8.13 – Given Attachment E of the U.S. National SAR Supplement to the International Aeronautical and Maritime SAR Manual, grid a sectional. Expired gridded charts may be used only for reference or training purposes (gridding). Label them “For Training Purposes Only”

CAP Conventional Grid System Overlays standard sectional maps Subdivides the map into distinct working areas Each grid is 1/4° (15 minutes) of latitude by 1/4° of longitude and is assigned a number Grids are further divided into sub-grids labeled A, B, C, and D Each sectional has a standard for assigning grid numbers — for areas of overlap the grid number of the most westerly chart is used Only a couple of charts in the US have overlaps. Where charts overlap, the grids on all charts will be assigned the number and identifier of the primary chart (the most westerly chart will be designated as the primary chart). Overlapping chart grids will use the identifier of the primary chart (e.g. MKC for Kansas City) and the grid number.

CAP Conventional Grid System Each grid on the sectional is assigned a number In this example, the grid depicted is on the St Louis Sectional STL 159 Grids are subdivided into smaller sections Letters are used to define sub-grids STL 159A 102-15 W 102-00 W 36-15 N A B 8.10.1 Objective 8.12 – State the size of a full and a one-quarter standardized grid. The first full 15-minute quadrangle in the northwest corner of the chart is numbered “One” and numbered in sequence from west to east. Continue in this manner until reaching the southeast corner of the gridded area which serves as the last full 15 minute quadrangle. 36-07.5 N C D 36-00 N 102-07.5 W 102 15’ W 102-00 W

Cell Grid System Can be used on any kind of chart that has lines of lat/long 1° blocks identified by the intersection of whole numbers of lat/long, such as 36-00N and 102-00W Points are designated with the latitude first (36 /102) and they identify the area north and west of the intersection of these two lines Grids can be subdivided into smaller sections Letters are used to define sub-grids Alternate system to CAP Grid System.

Marking Grid Charts You can use a new sectional — normally not updated unless it gets worn out Use a Hi-Lighter (not pink) to mark grid boundaries on the chart using a long ruler Mark grid identification in black ink for easy visibility You should always keep a current sectional with you even if you have a sectional which is marked with grids You can make a master grid chart and then mark up your current navigation chart with selected grids as needed. Red or pink marks on your charts will not be visible at night when the red light is the only light on. Use a green flashlight to see most colors.

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